\( \Large L \xrightarrow{+1}{} M \)
\( \Large U \xrightarrow{+0}{} U \)
\( \Large T \xrightarrow{+0}{} T \)
\( \Large E \xrightarrow{+0}{} E \)

Similarly,
\( \Large G \xrightarrow{+1}{} H \)
\( \Large A \xrightarrow{+0}{} A \)
\( \Large T \xrightarrow{+0}{} T \)
\( \Large E \xrightarrow{+0}{} E \)

Hence blue will be coded as
\( \Large B \xrightarrow{+1}{} C \)
\( \Large L \xrightarrow{+0}{} L \)
\( \Large U \xrightarrow{+0}{} U \)
\( \Large E \xrightarrow{+0}{} E \)

BLUE will be written as "CLUE"